... 3years use Shockproof design for vehicle use Smoke and Carbon Monoxide Detector HM-621THS• Stand alone, akaline battery operated, over 3 ... interference• Anti RF Interference (20v/m -1GHz)Smoke and Carbon Monoxide Detector Technical Pramaters: Operating VoltageDC 3V (2pcs AA alkaline ... mountedDimensionΦ110*45mmExecute CriterionEN50291, UL217, GB15322.5-233 Smoke and Carbon Monoxide Detector HM-621THS